alert http $EXTERNAL_NET any -> $HTTP_SERVERS any (msg:"ET WEB_SERVER WebShell Generic eval of base64_decode"; flow:established,from_server; file_data; content:"base64_decode"; nocase; fast_pattern; content:"eval"; nocase; pcre:"/^[\r\n\s]*?\x28[\r\n\s]*?base64_decode/Rsi"; classtype:trojan-activity; sid:2017399; rev:8; metadata:created_at 2013_08_31, confidence Medium, signature_severity Major, updated_at 2019_10_08;)